Aptamer- and Fab’- Functionalized Microring Resonators for Aflatoxin M1 Detection

Silicon oxynitride (SiON) microring resonators are used to develop a biosensor device to detect Aflatoxin M1 (AFM1), a carcinogenic mycotoxin present in milk. Two different surface functionalization strategies are tested to realize an affinity biosensing device. Both strategies are based on the formation of a silane surface layer able to bind either specific DNA-aptamers or antigen binding fragments (Fab'). The sensing device consists of an array of four SiON microring resonators, fiber-coupled to a vertical cavity surface emitting laser operating at 850 nm. Detection is realized with off-chip silicon photodetectors. With both functionalizations, we demonstrate a specific detection of AFM1 in buffer, while the nonspecific detection of Ochratoxin is not occurring. Repeatability and reproducibility of both functionalization strategies are discussed.